The invention relates to a gas bag module.
Known gas bag modules comprise a gas bag which has a gas bag wall with a front wall section, and a cover which has a given annular section closing an annular outlet opening for the gas bag and has a stationary central portion which is surrounded by the annular section. Such gas bags differ from others used hitherto by the annular outlet opening. The central portion remains stationary on opening of the covering, i.e. it is not swung outwards. An advantage connected with this design consists in that a large flap which swings outwards is no longer formed on the covering. The annular section usually consists of small segments adjoining each other peripherally, which serve as flaps but which take up a very small amount of space and also scarcely project into the passenger interior after opening. The gas bag modules with stationary central portion are hitherto to have had an annular gas bag, by the front wall section of the gas bag, which faces the occupant, being prevented from emerging from the module in the region of its center. The resultant centric indentation is kept small or closed by the most varied of measures.
The invention provides a gas bag module in which an indentation is no longer present in the region of the front wall section. This is achieved in a gas bag module which comprises a gas bag which has a gas bag wall with a front wall section. The module further comprises a cap-shaped cover which has a given annular section which closes an annular outlet opening for the gas bag and has a stationary central portion which is surrounded by the annular section. The gas bag wall has an outflow opening which in a folded state is arranged beneath the central portion in such a manner that on outlet of the gas bag, the central portion arrives via the outflow opening into an interior of the gas bag. The outflow opening is situated in sections of the gas bag other than the front wall section, i.e. in a side or rear wall section. The gas bag is therefore folded such that the edge of the outflow opening slides past the central portion on unfolding, therefore, the latter moves relative to the gas bag wall into the interior of the gas bag. Through the fact that, however, the outflow opening is situated outside the front wall section, i.e. the section onto which the occupant strikes, the front wall section is closed, without it featuring an opening or indentation. The outflow opening itself can then serve to vent the gas bag or to give it a different hardness on impact of the occupant. The outflow opening consequently has a dual function.
Preferably, in the inflated gas bag the outflow opening is to lie on its rear wall section, i.e. facing away from the occupant.
According to the preferred embodiment, the gas bag module is a steering wheel module, because in steering wheels the distance of the head of the occupant from the covering is usually less than in a passenger module, so that the advantage of the annular outlet opening comes into use particularly here.
The central portion is preferably permanently arrested on the module by means of a fastening piece, in particular a rigid fastening piece. The fastening piece projects in the folded state of the gas bag through the outflow opening and can therefore form a guide for the edge of the outflow opening on emergence from the module.
According to an embodiment, the central portion comprises or is an emblem constructed as a separate part. The emblem can be provided externally on a stationary section of a plastic cover part. The emblem, hitherto, had to be fastened with a great deal of effort to the flaps, which have a large area and swing outwards. In the gas bag module according to the invention, the emblem is at least part of the central portion and remains at its original place, despite the gas bag moving in outward direction.
The emblem can either be fastened to the stationary section or to a fastening piece, in the latter case preferably the fastening of the emblem also serving for that of the stationary section to the fastening piece, in order to save parts.
The cover can also be formed from various individual parts, which are not connected with each other in one piece, for example the annular section and the central portion. The central portion can also, for example, only be formed by the emblem. This embodiment has the advantage that on opening of the cover, smaller forces are necessary, because the central portion and the annular section are, originally, separate parts. According to a further embodiment, a stationary section defining one piece with the annular section per se or together with the emblem, arranged on its outer side, defines the central portion.